U.S. patent application number 10/393319 was filed with the patent office on 2004-09-23 for electrical adapter for medical diagnostic instruments using leds as illumination sources.
This patent application is currently assigned to Welch Allyn, Inc.. Invention is credited to Briggman, Shawn A., Davis, Peter J., Fahrenkrug, Corinn C., Krauter, Allan I., Pasik, Michael A., Roberts, Chris R., Salvati, Jon R., Stewart, Charles N., Strom, John R., Vivenzio, Robert L..
Application Number | 20040183482 10/393319 |
Document ID | / |
Family ID | 32988120 |
Filed Date | 2004-09-23 |
United States Patent
Application |
20040183482 |
Kind Code |
A1 |
Roberts, Chris R. ; et
al. |
September 23, 2004 |
Electrical adapter for medical diagnostic instruments using leds as
illumination sources
Abstract
An adapter for permitting a medical diagnostic instrument having
an illumination source including at least one LED (light emitting
diode) to be used with a power supply normally configured for use
with a diagnostic instrument having at least one incandescent lamp
as an illumination source. The adapter includes circuitry for
compensating LED specific characteristics for permitting the power
supply to be used with the LED.
Inventors: |
Roberts, Chris R.;
(Skaneateles, NY) ; Fahrenkrug, Corinn C.;
(Liverpool, NY) ; Krauter, Allan I.; (Skaneateles,
NY) ; Briggman, Shawn A.; (Syracuse, NY) ;
Pasik, Michael A.; (Auburn, NY) ; Davis, Peter
J.; (Skaneateles, NY) ; Strom, John R.;
(Moravia, NY) ; Stewart, Charles N.; (Skaneateles,
NY) ; Salvati, Jon R.; (Skaneateles, NY) ;
Vivenzio, Robert L.; (Auburn, NY) |
Correspondence
Address: |
WALL MARJAMA & BILINSKI
101 SOUTH SALINA STREET
SUITE 400
SYRACUSE
NY
13202
US
|
Assignee: |
Welch Allyn, Inc.
|
Family ID: |
32988120 |
Appl. No.: |
10/393319 |
Filed: |
March 20, 2003 |
Current U.S.
Class: |
315/363 ;
315/291 |
Current CPC
Class: |
A61B 1/227 20130101;
Y10S 323/911 20130101 |
Class at
Publication: |
315/363 ;
315/291 |
International
Class: |
G05F 001/00 |
Claims
We claim:
1. An adapter for use with a medical diagnostic instrument
typically configured with an incandescent lamp as an illumination
source and a power supply for powering said incandescent lamp, said
adapter having means for permitting at least one LED to be used as
the illumination source for said instrument while permitting said
existing power supply to used therewith.
2. An adapter as recited in claim 1, wherein said at least one LED
is a white LED.
3. An adapter as recited in claim 1, including means for limiting
the current supplied to said at least one LED by said existing
power supply.
4. An adapter as recited in claim 3, including means for boosting
the voltage supplied to said at least one LED by said existing
power supply.
5. An adapter as recited in claim 1, including means for
compensating the current drawn by said at least one LED from said
existing power supply.
6. An adapter as recited in claim 5, including means for boosting
the voltage supplied to said at least one LED by said existing
power supply.
7. An adapter as recited in claim 1, including means for matching
the polarity between said at least one LED and said existing power
supply.
8. An adapter as recited in claim 7, including means for limiting
the current to said at least one LED from said existing power
supply.
9. An adapter as recited in claim 7, including means for
compensating the current drawn by said at least one LED from said
existing power supply.
10. An adapter as recited in claim 8, including means for boosting
the voltage supplied to said at least one LED from the existing
power supply.
11. An adapter as recited in claim 9, including means for boosting
the voltage supplied to said at least one LED from the existing
power supply.
12. An adapter as recited in claim 1, including means for
compensating the voltage supplied to said at least one LED from
said existing power supply.
13. An adapter as recited in claim 12, wherein said voltage
compensating means includes means for boosting the voltage supplied
to said at least one LED.
14. An adapter as recited in claim 1, including means for
compensating the light output of said at least one LED.
15. An adapter as recited in claim 14, wherein said light output
compensating means includes means for boosting the voltage supplied
to said at least one LED.
16. An adapter as recited in claim 14, including means for dimming
said at least one LED.
17. An adapter as recited in claim 1, including means for
compensating the color sense of said at least one LED.
18. An adapter as recited in claim 17, including wherein said color
compensating means includes means for boosting the voltage of said
at least one LED.
19. An adapter as recited in claim 17, including at least one
optical filter.
20. An adapter as recited in claim 1, wherein said adapter includes
said at least one LED.
21. An adapter as recited in claim 1, including at least one
optical element disposed in relation to said at least one LED used
as the illumination source.
22. An adapter as recited in claim 21, including at least one
optical filter disposed in relation to said at least one optical
element.
23. In combination, an adapter for use with a medical diagnostic
instrument, said instrument including a power supply, electrically
configured for powering an incandescent bulb as an illumination
source, said instrument including an instrument head, a
hand-grippable handle and at least one LED disposed in said
instrument as the illumination source of said instrument, said
adapter including means for electrically interconnecting said power
supply and said at least one LED for effectively energizing said at
least one LED.
24. A combination as recited in claim 23, wherein said adapter is
independently attached between said instrument head and said
handle.
25. A combination as recited in claim 23, wherein said at least one
LED is part of an LED module.
26. A combination as recited in claim 25, wherein said adapter is
disposed in said LED module.
27. A combination as recited in claim 25, wherein said module
includes at least one optical element disposed in relation to the
output of said LED.
28. A combination as recited in claim 23, wherein said adapter is
disposed in said instrument head.
29. A combination as recited in claim 23, wherein said adapter is
disposed in the hand-grippable handle.
30. A combination as recited in claim 23, wherein said adapter is
disposed in the power supply of said instrument.
31. A combination as recited in claim 23, wherein said adapter
permits said at least one LED to be energized by said power supply
without modification thereof.
32. A combination as recited in claim 31, wherein said instrument
includes at least one of at least one LED and an incandescent lamp
as the illumination source for said instrument, said combination
further including means for selectively activating said adapter
depending on the illumination source provided in said
instrument.
33. A combination as recited in claim 32, including means for
sensing the type of illumination source in said instrument.
34. A combination as recited in claim 32, including mode switching
means connected to said adapter for enabling said adapter if at
least one LED is used as the instrument illumination source.
35. A combination as recited in claim 33, wherein said illumination
sensing means includes means for sensing whether there is a
polarity difference between said power supply and the illumination
source and means for automatically enabling said adapter if there
is a sensed polarity difference.
36. A combination as recited in claim 29, wherein said handle is
modified to permit use of said at least one LED.
37. A combination as recited in claim 30, wherein said power supply
is modified to permit use of said at least one LED.
38. A combination as recited in claim 24, wherein said instrument
head and said hand-grippable handle include interconnect means for
interconnecting said head to said handle for providing a mechanical
interface and maintaining an electrical interface between said
power supply and an incandescent lamp when an incandescent lamp is
typically used in the instrument, and in which said adapter
includes respective ends adapted to connect to said interconnect
means to provide said mechanical interface while creating an
electrical interface between said power supply and said at least
one LED.
39. A combination as recited in claim 38, wherein said at least one
LED is disposed in an LED module.
40. A combination as recited in claim 39, wherein said LED module
is disposed in said instrument head.
41. A combination as recited in claim 39, wherein said LED module
is disposed in said adapter.
42. A combination as recited in claim 23, wherein said at least one
LED is disposed in the instrument head.
43. A combination as recited in claim 23, wherein said at least one
LED is disposed in the adapter.
44. A combination as recited in claim 23, wherein said at least one
LED is a white LED.
45. A method for adapting a medical diagnostic instrument for use
with at least one LED as an illumination source, said instrument
including a power supply typically only electrically configured for
energizing an incandescent lamp as an illumination source, said
method comprising the steps of: adding an adapter to at least one
of said instrument head, said instrument handle and said instrument
power supply and electrically connecting said adapter to said power
supply and said at least one LED to energize same without
modification to said power supply.
46. A method as recited in claim 45, including the step of limiting
the current supplied to said at least one LED by said power
supply.
47. A method as recited in claim 45, including the step of
adjusting the voltage supplied to said at least one LED by said
power supply.
48. A method as recited in claim 45, including the step of
compensating the current drawn by said at least one LED from said
power supply.
49. A method as recited in claim 48, including the step of boosting
the voltage supplied to said at least one LED by said power
supply.
50. A method as recited in claim 45, including the step of matching
the polarity between said at least one LED and said power
supply.
51. A method as recited in claim 50, including the step of limiting
the current to said at least one LED from said power supply.
52. A method as recited in claim 50, including the step of
compensating the current drawn by said at least one LED from said
power supply.
53. A method as recited in claim 51, including the step of boosting
the voltage supplied to said at least one LED from the power
supply.
54. A method as recited in claim 52, including the step of boosting
the voltage supplied to said at least one LED from the power
supply.
55. A method as recited in claim 45, including the step of
compensating the voltage supplied to said at least one LED from
said power supply.
56. A method as recited in claim 55, wherein said voltage
compensating step includes the step of boosting the voltage
supplied to said at least one LED.
57. A method as recited in claim 45, including the step of
compensating the light output of said at least one LED.
58. A method as recited in claim 57, wherein said light output
compensating step includes the step of boosting the voltage
supplied to said at least one LED.
59. A method as recited in claim 57, including the step of dimming
said at least one LED.
60. A method as recited in claim 45, including the step of
compensating the color sense of said at least one LED.
61. A method as recited in claim 60, wherein said color
compensating step includes the step of boosting the voltage of said
at least one LED.
62. A method as recited in claim 60, including the step of
optically filtering said at least one LED.
63. A method as recited in claim 45, including the step of
disposing said at least one LED into said adapter.
64. A method as recited in claim 45, including the step of coupling
at least one optical element in relation to the output of said at
least one LED.
65. A method as recited in claim 64, including the step of placing
at least one optical filter in relation to said at least one
optical element.
66. A method as recited in claim 45, including the step of
independently attaching an adapter between said instrument head and
said handle.
67. A method as recited in claim 66, wherein said at least one LED
is part of an LED module and in which said method includes the step
of disposing said adapter in said LED module.
68. A method as recited in claim 45, wherein said instrument
includes at least one of at least one LED and an incandescent lamp
as the illumination source for said instrument, method including
the additional step of selectively activating said adapter
depending on the illumination source provided in said
instrument.
69. A method as recited in claim 68, including the step of sensing
the illumination source in said instrument.
70. A method as recited in claim 69, wherein said illumination
sensing step includes the additional steps of determining if there
is a polarity difference between said power supply and the
illumination source and automatically enabling said adapter if
there is a sensed polarity difference.
71. A method as recited in claim 66, including the step of
providing a mechanical interface between said instrument head and
said instrument handle that maintains an electrical interface
between said power supply and said at least one LED, said at least
one LED being located in one of the instrument head and the
adapter.
72. A method for adapting a existing medical diagnostic instrument
so as to incorporate at least one white LED as an illumination
source, said existing instrument including a power supply for
energizing a miniature incandescent bulb as an illumination source,
said instrument including an existing instrument head and a
existing instrument handle wherein said existing instrument head
and said existing instrument handle include mating interconnecting
ends which interlock said instrument head and said handle in a
mechanical interconnection while simultaneously maintaining an
electrical interface between said incandescent lamp and said power
supply, said method including the steps of: attaching an adapter
between said instrument head and said instrument handle, said
adapter including means for electrically interconnecting at least
one LED and said power supply as well as means for mechanically
interconnecting said instrument head and said instrument handle;
and mounting said at least one LED in one of said adapter and said
instrument head.
73. A method as recited in claim 72, including the step of
attaching a new instrument head having said at least one LED to
said adapter.
74. A method as recited in claim 72, including the steps of
removing said incandescent bulb from said instrument head and
mounting said existing instrument head onto said adapter, wherein
said at least one LED is disposed in said adapter.
Description
FIELD OF THE INVENTION
[0001] The following application generally relates to the field of
illumination, and more particularly to an LED illumination system
intended for use with hand held medical diagnostic instruments,
such as those used in a physician's or health care provider's
office, or other medical environments.
BACKGROUND OF THE INVENTION
[0002] Many manufacturers of hand-held medical diagnostic
instrument products including otoscopes, ophthalmoscopes, et al.,
such as those from Heine Inc., Welch Allyn, Inc., and Keeler
Instruments, among others, have long since utilized miniature
incandescent lamps, such as halogen and xenon lamps, as
illumination sources. These lamps are typically provided within the
handle or the head of the instrument and utilize fiber optic
bundles or other optical means to transmit the light from the
miniature lamp to the tip opening of the diagnostic instrument,
such as an ophthalmoscope, otoscope, or similar device.
[0003] Power sources for these lamps are typically either wall
mounted or are portable, in the form of batteries provided in the
instrument handle and having a nominal voltage of approximately 2.5
or 3.5 volts. These voltages are convenient values, since they
match both a stacked arrangement of two or three Nickel cadmium
batteries and 3.5 volts in particular is favored since it is also
the voltage of a single lithium ion cell. Examples of instruments
having same are described, for example, in U.S. Pat. Nos.
4,012,686, 5,559,422, 5,177,424, and 5,542,904.
[0004] More recently, there has been considerable interest in the
field in light emitting diodes (LEDs) as a potential substitute for
miniature incandescent lamps. White versions of these LEDs, such as
those described, for example, in U.S. Pat. Nos. 6,069,440 and
5,998,925, among others, the entire contents of which are herein
incorporated by reference, provide better illumination capability
than predecessor LEDs and are therefore coveted for a myriad of
applications due to their longer life, resistance to shock and
impact loads, cooler operating temperatures and alternative
spectral content as compared with the afore mentioned miniature
incandescent lamps. Moreover and adding LEDs in general, such as
color LEDs, provide additional benefits such as spectral tuning,
IR, spectrally specific illumination, and the like.
[0005] It is a general desire in the field that future product
improvements incorporating white LEDs as illumination sources be
compatible with both the mechanical and electrical features of
existing power supplies to which these instruments are
interconnected. There are, however, a number of significant
differences which must be recognized in the incorporation of the
above illumination devices into any previously known medical
diagnostic instrument. For example, white LEDs, such as those
described above, experience a large variation in forward voltage as
compared with miniature incandescent lamps, as well as significant
differences in current versus light output and color
characteristics. There are also mechanical issues relating to the
incorporation of any adapter into a medical diagnostic
instrument.
[0006] In summary, there is a need to develop an adaptive means
which can be mechanically, optically and electrically incorporated
into the design of a hand-held medical diagnostic instrument so as
to permit an instrument having LEDs as an illumination source to be
readily used with a variety of existing power supplies and charging
apparatus. There is an additional need to enable current instrument
heads which formerly used miniature incandescent lamps to utilize
white or color LEDs with these existing power sources.
SUMMARY OF THE INVENTION
[0007] It is therefore a primary object of the present invention to
overcome the above-noted deficiencies of the prior art.
[0008] It is another primary object of the present invention to
develop electrical adapters that can permit LEDs, such as white
LEDs, to be utilized in existing known hand-held medical diagnostic
instruments without requiring major configuration changes to
already existing power supplies and/or electrical charging
apparatus.
[0009] It is yet another primary object of the present invention to
provide an electrical adapter which permits white LEDs to be
utilized in already existing hand-held diagnostic instruments, such
as otoscopes, without significantly impacting the mechanical and/or
optical function or design of the instruments.
[0010] Therefore and according to a preferred aspect of the
invention, there is provided an electrical adapter for use with a
medical diagnostic instrument typically configured with an
incandescent lamp as an illumination source and a power supply for
powering said incandescent lamp, said adapter having means for
permitting at least one LED to be used as the illumination source
for said instrument while permitting said existing power supply to
used therewith.
[0011] Preferably, means are included for compensating LED-specific
characteristics for permitting the power supply to be used with the
medical diagnostic instrument. The adapter preferably includes an
AC to DC converter in order to compensate for variations in forward
voltage of at least one white LED used as an illumination source
and to effect polarity discrepancies. The AC to DC converter can
consist of, for example, at least one diode bridge or a MOSFET
switch. The adapter also preferably includes means for compensating
LED specific differences such as current, voltage boost,
regulation, and color sense, thereby permitting use of the
diagnostic instrument having at least one white LED with already
existing power supplies and/or battery charging apparatus.
[0012] According to one preferred embodiment, the LED electrical
adapter can be disposed within the head of the diagnostic
instrument so as to permit interchangeability of illumination
devices; that is, in which one interchangeable instrument head can
include a miniature incandescent lamp and another interchangeable
head includes a least one white LED and an electrical adapter
permitting the LED to be utilized with the remainder of the
instrument whether the instrument includes a wall mounted power
supply or batteries.
[0013] Alternatively and according to yet another preferred
embodiment, the LED electrical adapter can be fitted in lieu of a
conventional battery within the instrument handle. The adapter, in
fact, can be manufactured and sized so as to effectively replace a
battery within the handle.
[0014] According to yet another preferred aspect of the invention,
there is provided in combination, an adapter for use with a medical
diagnostic instrument, said instrument including a power supply,
electrically configured for powering an incandescent bulb as an
illumination source, said instrument including an instrument head,
a hand-grippable handle and at least one LED disposed in said
instrument as the illumination source of said instrument, said
adapter including means for electrically interconnecting said power
supply and said at least one LED for effectively energizing said at
least one LED.
[0015] According to still another preferred aspect of the present
invention, there is provided a method for adapting a medical
diagnostic instrument for use with at least one LED as an
illumination source, said instrument including a power supply
typically only electrically configured for energizing an
incandescent lamp as an illumination source, said method comprising
the steps of:
[0016] adding an adapter to at least one of said instrument head,
said instrument handle, and said instrument power supply; and
electrically connecting said adapter to said power supply and to
said at least one LED to energize same without modification to said
power supply.
[0017] According to yet another preferred aspect of the invention,
there is provided a method for adapting a existing medical
diagnostic instrument so as to incorporate at least one LED as an
illumination source, said existing instrument including a power
supply for energizing a miniature incandescent bulb as an
illumination source, said instrument including an existing
instrument head and a existing instrument handle wherein said
existing instrument head and said existing instrument handle
include mating interconnecting ends which interlock said instrument
head and said handle in a mechanical interconnection while
simultaneously maintaining an electrical interface between said
incandescent lamp and said power supply, said method including the
steps of:
[0018] attaching an adapter between said instrument head and said
instrument handle, said adapter including means for electrically
interconnecting at least one LED and said power supply as well as
means for mechanically interconnecting said instrument head and
said instrument handle; and
[0019] mounting said at least one LED in one of said adapter and
said instrument head.
[0020] An advantage of the present invention is that the herein
described electrical adapter permits a number of hand-held medical
diagnostic instruments to be used with any previously existing
power supplies or battery charging apparatus used therein without
significant modification.
[0021] Still another advantage of the present invention is that the
herein described electrical adapter permits each of the advantages
of LEDs to be brought to the diagnostic instrument. These
advantages which include longer lamp life, longer battery life,
reduced maintenance, and higher reliability without significantly
impacting cost which heretofore could not easily be brought to the
instrument without significant redesign of the electrical
system.
[0022] These and other objects, features, and advantages will
become readily apparent from the following Detailed Description
which should be read in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a partial side section view of the head of a prior
art medical diagnostic instrument;
[0024] FIG. 2 is a partial side sectioned view of the medical
diagnostic instrument of FIG. 1, including a portable battery power
source;
[0025] FIG. 3 is a front view of another prior art medical
instrument including a wall-mounted power supply;
[0026] FIG. 4 is a side perspective view of a prior art diagnostic
instrument illustrating the interconnection between an instrument
head and the instrument handle/power supply;
[0027] FIG. 5 is an enlarged side perspective view of the
instrument head/handle-power supply interconnection of FIG. 4;
[0028] FIG. 6 is a partial side view of the interconnection between
another prior art instrument head and instrument handle;
[0029] FIG. 7 is an unassembled view of the instrument of FIG.
6;
[0030] FIG. 8 is a schematic block diagram of an LED electrical
adapter made in accordance with the present invention;
[0031] FIG. 9 is an electrical circuit diagram of an embodiment of
the LED electrical adapter of FIG. 8;
[0032] FIG. 10 is an electrical circuit diagram of a current
compensation portion of the LED electrical adapter of FIG. 8;
[0033] FIG. 11 is a side elevational view, partially in section, of
a medical diagnostic instrument having an LED electrical adapter
made in accordance with a preferred embodiment of the present
invention;
[0034] FIG. 12 is a side elevational view, partially in section, of
a medical diagnostic instrument having an LED electrical adapter
made in accordance with another preferred embodiment of the present
invention;
[0035] FIGS. 12(a) and 12(b) are side elevational views of a
diagnostic instrument head, partially in section, including means
for detecting the illumination mode of the head in accordance with
a preferred embodiment of the present invention;
[0036] FIG. 13 is a side elevational partial perspective view of a
LED electrical adapter for a medical diagnostic instrument made in
accordance with yet another preferred embodiment of the present
invention;
[0037] FIG. 14 is a side perspective view of the LED electrical
adapter of FIG. 13;
[0038] FIG. 15 is a side elevational view of a portion of the
adapter of FIGS. 13 and 14; and
[0039] FIG. 16 is a circuit diagram of a microcontroller system for
detecting the presence of an incandescent bulb or an LED.
DETAILED DESCRIPTION
[0040] The following description relates in general to an LED
electrical adapter that can be used in a hand-held medical
diagnostic instrument, such as an ophthalmoscope, otoscope,
vaginoscope, and the like, though the embodiments described herein
detail a specific instrument, namely an otoscope.
[0041] Prior to discussing the invention and referring to FIGS. 1
and 2, there is first shown a medical hand-held diagnostic
instrument that is already known in accordance with the prior art.
In this instance, the diagnostic instrument 10 is a conventional
otoscope, used for the examination of the outer ear, including the
tympanic membrane. This instrument 10 generally includes a hollow
instrument handle 14 and an instrument head 18 that is attached to
the top of the handle. The instrument head 18 is hollow and
includes a frusto-conical tip portion 40 onto which a disposable
speculum (not shown) is fitted in a conventional manner, such as a
bayonet 44. The speculum is sized for fitting a predetermined
distance into the ear canal of a patient, the tip portion 40 having
a distal tip opening 42. An eyepiece 46 attached to the proximal
end 48 of the instrument head 18 forms an optical path with the
distal tip opening 42 through the hollow instrument head 18 to
permit viewing of the medical target.
[0042] A miniature incandescent lamp 22, such as a halogen or xenon
lamp, is provided in a lamp housing 25 that is disposed in a base
27 of the instrument head 18, the lamp being electrically connected
through a contact 29 and a vertically extending pin 31 to a series
of stacked Nickel cadmium batteries 26 that are retained in a
bottom compartment of the instrument handle 14 for energizing the
lamp 22. The instrument handle 14 also contains a bottom or lower
contact spring 33. An adjustable voltage control 30 located on the
exterior of the upper portion of the instrument handle 14
selectively adjusts the amount of illumination output provided by
the miniature lamp 22.
[0043] In addition to the above and referring to FIGS. 4-7, an
effective mechanical interface is essential in order to maintain
electrical contact between a miniature incandescent lamp contained
in the head in the manner detailed above and the contained power
supply. A pair of prior art instruments 10A, 10B therefore each
include a mechanical interface between the instrument head 18A, 18B
and the upper end of the instrument handle 14A, 14B such that when
the instrument head is attached to the handle that the above
electrical connection is maintained between the lamp and the power
supply for the instrument.
[0044] In the prior art examples illustrated in FIGS. 4-7, each of
the instruments employ a form of a bayonet connection. In the
instrument according to FIGS. 4 and 5, the base 27A of the
instrument head 18A includes an interior set of slots (not shown)
for engaging a circumferential set of ears 32 (only one being
shown) provided on the exterior of the upper portion 28A of the
handle 14A. A functionally similar instrument is shown in FIGS. 6
and 7 for an ophthalmoscope in which the base 27B includes a set of
ears 37 for engaging a corresponding set of slots located in the
upper portion 28B of the instrument handle 14B to permit the
electrical contact 39 to be placed into electrical contact with the
power supply of the instrument to permit illumination of the lamp
disposed within the base 27B. Other suitably similar interfaces can
be utilized as these depicted are intended only to be exemplary. In
addition, it is known that by maintaining these mechanical and
electrical interfaces/connections that various instrument heads
and/or handles, including those from different manufacturers, can
be combined in a single hand-held instrument.
[0045] Alternately and in lieu of batteries, a hand-held medical
diagnostic instrument handle 50 can be tethered by means of a cord
52 directly to a wall transformer or similar power supply 54, such
as shown in FIG. 3. In each particular instance and referring to
FIG. 1, a series of optical fibers 38 extend from the miniature
incandescent lamp 22 through the base 27 of the instrument head 18,
to a bundle of light transmitting ends 36 or other optical means
that are disposed at the distal tip opening 42 in order to provide
illumination of the medical target (e.g., the tympanic membrane).
One typical wall transformer is further described in U.S. Pat. No.
5,559,422, incorporated herein in its entirety.
[0046] With the preceding background and referring now to FIG. 8,
there is shown a block diagram of an LED electrical adapter 60 made
in accordance with a preferred embodiment of the present invention.
This electrical adapter 60 includes a number of primary features
that are required in order to permit already existing power
supplies, such as those shown in FIGS. 1-7, to be used in
conjunction with at least one white LED package 64 that would be
substituted for the miniature incandescent lamp 22, FIG. 1, in a
medical diagnostic instrument.
[0047] As will be apparent from the following discussion, the
mechanical and electrical design of the inventive adapter can
assume a plurality of electrical, mechanical and electrical
configurations covered in general by all or some features of the
block diagram of FIG. 8, permitting the adapter to be used in
conjunction with literally any existing power supply that provides
power to an incandescent lamp-equipped medical diagnostic
instrument.
[0048] In general, the LED electrical adapter 60 includes a voltage
conversion portion 84 and a compensation portion 100. Each of these
features will now be described in greater detail. It should be
noted that for illustration purposes that the compensation portion
is presumed to be a current compensation portion, although other
characteristics such as voltage, light output and/or color
compensation are similarly implemented.
[0049] First, the voltage conversion portion 84 herein is an AC or
DC converter which can be constructed, for example, as a simple
diode bridge so as to provide proper selection of the forward
voltage drop of at least one white LED package 64. Alternately,
there are a number of so-called "no drop" MOSFET switches, such as
those manufactured by Vishay-Siliconix, among others, could
preferably facilitate the voltage conversion with minimal loss in
power. Provision of this conversion portion 84 permits both AC and
DC power supplies to utilized. In addition, any polarity mismatch
between the LED package 64 and the previously utilized miniature
incandescent lamp 22 would also be corrected using this converter
portion.
[0050] That is to say, while miniature incandescent lamps are
unaffected by opposite polarity from a power source. LEDs require
unipolar DC current in order to illuminate.
[0051] The current compensation portion 100 can include each of the
following: a general current compensation means 104 for provided a
limited maximum current, and a high/low stopper regulator 108.
[0052] As far as simple current compensation is concerned, a
resistor or a PTC (positive thermal coefficient e.g., thermistor)
can be used, though it is believed this is not the optimal
solution. There are two reasons for this belief. First, there are
variabilities between LEDs in terms of output versus current.
Therefore, this "solution" provides partial compensation to an
"average" white LED in average conditions. Additionally, this form
of current compensation may not adequately compensate under low and
high supply voltage conditions because the resulting differential
voltage between the power source and the LED forward voltage will
be directly translated into current difference when using a PTC or
resistor as the compensating element. In some instances, the LED
forward voltage will be higher than the source voltage and
therefore no conduction will occur at all. For instance, a typical
3.5 volt battery power handle ranges between 3.0 volts and 4.2
volts and a typical white LED (such as, for example, a Lumileds
Luxeon LXHL-MWIA) has a forward voltage of between about 2.55 volts
and about 3.99 volts. These low voltage conditions would occur as
the batteries within the instrument handle discharge, or with low
line or power supplies that are set at the low end of their
manufacturing tolerances.
[0053] In addition, high voltage conditions could conversely cause
excessive current to flow, resulting in very poor color or in the
extreme, failure of the device itself. These high voltage
conditions would occur with new, fully charged batteries, or at
high line of power supplies set at the high end of manufacturing
tolerances.
[0054] Regulating/limiting systems for current compensation can
include for example, linear regulators, such as, for example, a
National Semiconductor LM1117. Alternately, a bimetallic switch can
be applied which can be set to create a duty cycle which averages a
corrected current in order to produce a stable consistent output as
long as the voltage provided by the power source is sufficiently
above the forward voltage of the LED.
[0055] Referring to FIG. 9, a circuit is herein described that
controls the voltage to an LED which is used in lieu of a miniature
incandescent bulb. As will be noted below and with relatively small
modification, the circuit can further be configured to control the
light output of the LED or the color output of the LED by selecting
the appropriate detector (photodiode with or without filter) and
connecting the detector to the sense feed line. The voltage control
circuit of FIG. 9 functions as follows:
[0056] An oscillator (U1) is assumed to be a voltage controlled
oscillator having a base frequency and a duty cycle that is a
function of the input voltage. There are many PWM (pulse width
modulation) type devices available, and this circuit does not rely
on any particular such device. Upon initial power up of the
circuit, the voltage across a pair of resistors (R2) and (R3) would
be zero, and the sense voltage would be zero. Once a comparator
(U2) powers up, the sense voltage (zero at start) will be compared
with the reference (U3) and a positive error signal will be
generated. This error is fed to the oscillator (U1) which increases
its on time cycle, thereby driving transistor (Q1) to turn on. The
preceding causes current to flow through an inductor (L1) and
stores energy as an electromagnetic field. During the "off" cycle
of the oscillator (Q1) turns off and all current is then fed
forward into a diode (D1). This feeding creates a voltage and
drives current into the LED when the voltage becomes higher than
the LED threshold (forward voltage) which is sensed via a pair of
voltage dividers (R2) and (R3). If this voltage remains lower than
the reference (U3), the error comparator (U2) continues to generate
a positive error and the oscillator continues to increase its pulse
width which increases the energy which is stored in (L1), and
consequently the output voltage into the LED. When the output and
therefore the sense voltage becomes higher than that of the
reference (U3), the error comparator (U2) generating a negative
error signal which decreases the oscillator on time to reduce the
output voltage. This process continues and maintains the output
close to the reference voltage that is selected. The reference
voltage is chosen to be the optimum setting for LED operation.
[0057] While the above is a basis version, it should be noted that
by including a resistor in series with the load, as shown in FIG.
10, rather than in parallel, this circuit represents a simplified
current control, as represented in compensation block 100, FIG. 8.
In addition, any other sensing means can be introduced such that
the above circuit would respond to other changes such as light
level, color, etc.
[0058] FIG. 9 includes a means for adequate energy storage in L1,
FIG. 9, to bring the apparent source voltage to the LED above the
forward voltage of the LED and then regulate the subsequent current
which is drawn. Alternately, the regulator can be replaced by a low
resistance MOSFET.
[0059] Including an oscillator to the design of the current
compensation portion as in FIG. 9 would also permit dimming of the
LED using either a duty cycle or a pulse width modulation
technique. Since LEDs do not dim gradually and predictably with a
decrease in voltage, use of the duty cycle would take advantage of
the LEDs relatively fast "on/off" time to create "apparent" dimming
for the user.
[0060] In addition, color will change as current is changed.
Therefore, directly decreasing current to adjust light output, for
example, will produce an undesirable variation in color. By
utilizing either a duty cycle or pulse width modulation as a
dimming "technique" for the LED, the LED is pulsed at virtually
full power, but for shorter periods of time and therefore appears
to dim. The current remains at the "normal" full on value during
these pulses, therefore the color of the LED does not perceivably
change as the LED is dimmed.
[0061] Depending on the degree of complexity and/or cost
considerations, the oscillator can be replaced with a bimetallic
element. This substitution also provides the opportunity to modify
the light output by rapidly pulsing the LED at a duty cycle which
represents the modified intensity desired.
[0062] Having described the basic circuitry and referring now to
FIGS. 11-15, a number of potential locations for the herein
described electrical LED adapter can be assumed, exemplary
embodiments being herein described. For example and first referring
to FIG. 11, there is illustrated a battery-powered diagnostic
instrument 120, such as previously described in FIGS. 1 and 2, that
further includes an adaptor module 124 carrying the electrical
circuitry of FIGS. 9 and/or 10, the module being disposed between
the instrument head 128 and the top of the handle 132. The adapter
124 includes a housing 136 including a resident printed circuit
board 140 and respective electrical contacts 144, 148 provided at
opposing ends of the housing. A white LED 152 such as described in
U.S. Pat. No. 5,998,925, previously incorporated above, is disposed
within a cavity 156 formed within the lower portion of the
instrument head 128 wherein the LED includes at least one contact
160 that is placed in proximity with the upper facing contact 144
of the adapter 124. The lower facing contact 148 of the adapter 124
is arranged in relation to the retained batteries 168 disposed
within the handle 132. A set of optics 172 are optionally disposed
in relation to the LED die for coupling with the illumination
output of the LED 152.
[0063] Referring to FIG. 12, a similarly designed LED electrical
adapter 176 can assume other locations relative to the medical
diagnostic instrument. The adapter 176, according to this
embodiment, is disposed within a cavity 180 formed within the
interior of the instrument head 177 along with an LED 188 having
contacts that engage a printed circuit board 190 having the
circuitry previously described. The adapter 176 further includes a
lower contact 194 that engages the batteries (not shown) provided
in the handle (not shown).
[0064] Referring to FIGS. 13-15, another embodiment of an LED
electrical adapter is provided that includes a compact cartridge
200 that is sized so as to replace an existing battery typically
retained within an instrument handle 204. The adapter cartridge 200
is preferably defined in a cylindrical shape and is sized similarly
to that of a contained battery to permit fitting into the
instrument handle 204 in lieu thereof. This electrical cartridge
includes a slot 208 that retains specific voltage conversion means
in the form of a voltage conversion means 220, having elements as
defined above, the cartridge being disposed between one of the
batteries 210 and the extending pin contact extending from the
instrument head (not shown) as well as an extending negative
contact strip 214 enabling a suitable electrical connection between
the battery 210 and the LED (not shown). Each of the above
assemblies can be retained in a housing (not shown for clarity) of
convenient size.
[0065] In addition to and in complement of the herein described
electrical adapter, an optical system can be added or modified to
improve color. For example, a suitable filter and a collection lens
can be placed at the light transmitting end of an LED having its
top lens removed. The filter may also be part of this lens and the
assembly may alternately be part of the LED or incorporated into
part of the instrument head.
[0066] In addition to and in complement of the herein described
electrical adapter, a means for detecting and switching the drive
electronics from an LED version to an incandescent lamp version of
a diagnostic instrument is beneficial, since this switching ability
allows the same instrument to take advantage of each illumination
system. There are several means for accomplishing this goal. The
most basic technique is the incorporation of a mode switch which is
manually actuated by the user of the instrument. This mode switch
would connect the illumination to either the incandescent lamp
drive circuitry or the LED drive circuitry based on the user's
discretion.
[0067] The operation of an exemplary switch configuration is
depicted in FIGS. 12(a) and 12(b) showing alternative illumination
sources as previously described. In FIG. 12(a), an incandescent
lamp 228 is disposed in a diagnostic instrument head 232, such as
an otoscope head, the incandescent lamp having leads 236, 240
extending to respective contact surfaces 244, 248. Contact surface
244 is located at the bottom of the lamp module 252 in a proximal
end of the instrument head while contact surface 248 is located
adjacent the lamp module 252. A third contact surface 256 is
established along the exterior of the instrument head 232, this
portion of the head being separated from contact surface 244 by an
insulator 260.
[0068] The operation of the mode switch is based upon the
combination of contact surfaces engaged. According to this
embodiment, the incandescent lamp 228 is energized by supplying
electrical energy from the handle or otherwise between contact
surfaces 256 and 244, each of which are in direct contact with the
lamp module 252.
[0069] In the embodiment of FIG. 12(b), on the other hand, an LED
module 266 is situated in the instrument head 232 wherein the LED
270 is energized by supplying electrical energy between contact
surfaces 244 and 248, each of which are in direct electrical
contact with the LED module through respective electrical contacts
274 and 278 via electrical adapter 60.
[0070] As described, the adapter can provide a means for different
contacts for the LED and the incandescent lamp, such that simply
inserting the desired illumination device automatically selects the
proper drive circuitry/configuration. In yet another alternative of
the invention, the mechanical contact geometry can be the same for
both illumination devices, and the adapter electronics can detect
the presence or lack of polarity whether the illumination is an LED
(polarized) or an incandescent bulb (not polarized). The above
objective can be accomplished, in a preferred embodiment, using a
microcontroller system such as illustrated in FIG. 16.
[0071] Referring to FIG. 16, a microcontroller U1 turns on half
H-bridges Q1/2 and Q3/4 sequentially and checks the resulting
voltage at resistors R1 and R2. If the resulting voltage is the
same, this provides an indicator that the current flow is symmetric
in both directions, indicating a non-polarized illumination device
and therefore the device located at U4 in this circuit would be
determined to be an incandescent lamp. If the voltage is different
between R1 and R2, the device would be determined to be polarized,
indicating that the device located at U4 is an LED. In addition,
the direction of polarity would also be known allowing the drive
circuitry to be properly connected. One further benefit of the
above detection scheme is that it would also allow detection of
blown lamps or LED's if the current flow in each direction tested
was found to be essentially zero. It is also noted that
microcontroller U1 is presumed to include an analog to digital
converter that is used to convert the analog voltage present at R1
and R2 to a digital reading. While there are several
microcontrollers which have this feature, the analog to digital
converter could be implemented separately if needed. Also, the
drive circuitry and connection to U4 is intentionally left out of
this diagram for the sake of simplicity and to convey the essential
concepts of the invention. However it should be obvious to one of
sufficient skill in the field that it can be accomplished even as
simply as adding additional H-bridge sections (not shown) under
microcontroller control.
[0072] Parts List for FIGS. 1-8 15]16
[0073] 10 medical diagnostic instrument
[0074] 10A, 10B diagnostic instrument
[0075] 14 instrument handle
[0076] 14A, 14B instrument handle
[0077] 18 instrument head
[0078] 18A, 18B instrument head
[0079] 22 miniature halogen lamp
[0080] 25 lamp housing
[0081] 26 batteries
[0082] 27 base
[0083] 27A, 27B base
[0084] 28A, 28B upper end
[0085] 29 contact
[0086] 30 adjustable voltage control
[0087] 31 pin
[0088] 32 ears
[0089] 33 contact spring
[0090] 36 light transmitting ends
[0091] 37 ears
[0092] 38 optical fibers
[0093] 39 contact pin
[0094] 40 tip portion
[0095] 42 distal tip opening
[0096] 44 bayonet
[0097] 46 eyepiece
[0098] 48 proximal end
[0099] 50 instrument handle
[0100] 52 cord
[0101] 54 wall transformer
[0102] 60 electrical LED adapter
[0103] 64 LED package
[0104] 84 AC or DC converter
[0105] 100 current compensation portion
[0106] 120 instrument
[0107] 124 adaptor module
[0108] 128 instrument head
[0109] 132 handle
[0110] 136 housing
[0111] 140 printed circuit board
[0112] 144 contact
[0113] 148 contact
[0114] 152 LED
[0115] 156 cavity
[0116] 160 contact
[0117] 168 batteries
[0118] 172 optics
[0119] 176 adapter
[0120] 177 instrument head
[0121] 180 cavity
[0122] 188 LED
[0123] 190 printed circuit board
[0124] 194 lower contact
[0125] 200 cartridge
[0126] 204 handle
[0127] 208 slot
[0128] 210 batteries
[0129] 214 negative contact strip
[0130] 220 voltage conversion means
[0131] 228 incandescent lamp
[0132] 232 instrument head
[0133] 236 lead
[0134] 240 lead
[0135] 244 contact surface
[0136] 248 contact surface
[0137] 252 lamp module
[0138] 256 contact surface
[0139] 260 insulator
[0140] 266 LED module
[0141] 270 LED
[0142] 274 electrical contact
[0143] 278 electrical contact
[0144] Though the following description has been made in terms of
certain embodiments, it will be readily apparent that other
modifications and variations are possible which encompass the
spirit and scope of the herein claimed invention.
* * * * *